1. Field of the Invention
The present invention relates to a corner detection device and a corner detection method, and a device and a method which are preferably applied to a video signal processing device wherein an image of another video signal is inserted in a predetermined frame of a background of a news anchorperson by photographing the anchorperson who reads news to generate the video signal and inserting the other video signal therein.
2. Description of the Related Art
Conventionally, in the manufacture of news programs, an image corresponding to the content of news is provided to viewers by inserting a video image corresponding to news content read by an anchorperson into a predetermined frame of the background of an anchorperson. As a consequence, viewers can understand the content of the news further in detail with the news manuscript read by the anchorperson and the video image presented at the background of the anchorperson.
The insertion processing of video signals is performed with a method which will be explained hereinbelow. At first, a source video signal representative of a video image (referred to as a source video image hereinafter) which should be inserted in a predetermined frame of the background of the anchorperson is generated (or reproduced from a VCR or the like) and is input to one input terminal of a mixer via a video effector. Furthermore, along with this, a studio video image signal is obtained by photographing the anchorperson in the studio, and the studio video signal is input to the other input terminal of the mixer. This mixer mixes a source video signal input to one and the other input terminals and the studio video signal, and a synthesized video signal obtained as a consequence is supplied to a monitor.
An operator supplies a parameter for expanding, reducing, moving, and rotating a source video image to a video effector via an input device such as a track ball or the like in such a manner that an outside form of the source video image corresponds to a predetermined frame of the background of the anchorperson while watching the synthesized image displayed on the monitor. The video effector expands, reduces, moves, and rotates the source video image on the basis of the parameter which is supplied and supplies to the mixer the source video signal which is subjected to the aforementioned processing, and a key signal representative of the configuration of the source video image after the aforementioned processing is performed. The mixer inserts the source video signal into a position represented on the basis of the key signal from out of the studio video signal. The synthesized video signal which is obtained as a consequence is supplied to the monitor to be displayed as described above. The operator supplies parameters for expansion, reduction, movement, and rotation to a video effecter in a repeated manner while watching the synthesized image which is displayed until an outside configuration of the source video image agrees with the predetermined frame of the background of the anchorperson. When such processing is repeated, the video source image is inserted into the predetermined frame of the background of the anchorperson in the conventional example.
Incidentally, in the conventional insertion processing, the operator must input parameters required for conversion processing such as expansion, reduction, movement, and rotation of the source video image until the configuration of the source video image agrees with the predetermined frame of the background of the anchorperson in a manual operation by using an input device such as a track ball or the like. As a consequence, a problem arises in that it takes a long time to get the source image configuration to agree with the predetermined frame of the background of the anchorperson accurately, and the operation becomes troublesome because a parameters input operation must be performed.
As a method for solving the problem, for example, U.S. Pat. No. 4,951,040 and U.S. Pat. No. 5,107,252 discloses such a method. In such a method, the operator uses input means such as a touch tablet, and a stylus or the like to input the corner position of at least four points representing a configuration after the conversion of the source video image. Then, the image conversion means converts the source video image on the basis of an address signal representing the corner position of four points which are input in such a manner that the corner of the source video image agrees with the corner of the designated four points. As a consequence, in this method, the source video image can be inserted into a predetermined frame in a relatively short time compared to the method described above, and the operation of the operator can be eased.
However, in these methods, in a case in which the source video image is inserted into the predetermined frame of the background of the anchorperson, the operator must input the corner position by manually operating input means such as a touch tablet, a stylus, and the like so that each corner of the source video image agrees with each corner of the predetermined frame of the background of the anchorperson with the result that the method is still insufficient in making the operation of the operator easy.
Incidentally, when the four corner positions of the predetermined frame located at the background of the anchorperson can be automatically detected from the studio video signal, the parameter of the image conversion is determined on the basis of the corner position. Thus, it seems that a video signal processing device can be realized which is capable of automatically inserting the source video image into the predetermined frame of the background of the anchorperson. In such a video signal processing device, the operation of the operator can be eased to a considerable degree, compared to the prior art, so that it seems that the condition of usage can be improved.